John s



(No Model.)

J. s. THOMPSON.

Patented Feb. 14,1882.

N. PETERS. Pholo-lilhngmphnr. Wnslnnglon. n, c.

UNITED STATES JOHN PATENT OFFICE.

S. THOMPSON, OF GREENVILLE, SOUTH CAROLINA, ASSIGNOR TO I MELVILLE M. JOHNSTON, OF NEW YORK, N.

DENTISTS CHAIR.

SPECIFICATION forming part of Letters Patent No. 253,640, dated February 14, 1882,

Application filed January 15, 1881. (No model.)

To all whom it may concern Be it known that I, JOHN S. THOMPSON, of Greenville, South Carolina, have invented certain new and useful Improvements in Dentists Chairs, of which the following is a specification.

My invention is designed with a view to rendering the body or seat-frame of a dentists chair capable of being tilted laterally and of being secured in place at any angle of lateral inclination to which it may be tilted, and is intended to be used in connection with a chairbody or seat-frame which can also be tilted backward andforward, and is provided with means for securing it in this adjustment. The particular dentists chair to which I have applied my improvement is the well-known Wit kerson chair, which has been in extensive use forsome years past, andis described and shown in Letters Patent to B. M. Wilkerson, dated November 20, 1877, No. 197,441.

In the accompanying drawings, in order to avoid confusion of parts, I have represented only so much of a 'Wilkerson chair as needed in order to explain my improvement.

Figure 1 is a plan of that part of the chair which contains my improvement, the upholstered seat being removed in order to show the parts underneath. Fig. 2 is a front elevation of the same with the seat-frame in section. Fig. 3 is a longitudinal section on line X X, Fig. 1.

Ais the plunger or post upon which the chair is supported and raised or lowered.

E is the frame which supports the upholstered seat B. (Shown in dotted lines in Figs. 2 and 3.)

The projections which in practice extend from theframe for carrying the back and the foot-rest of the chair are not shown, inasmuch as these parts do not relate to my improvement.

The frame E is adapted to oscillate backward and forward in the usual way on the trunnions d of the cross-head D, and is held fast in any desired position by the pin J, which enters one of the holes in the sector F, carried by the frame. The pin J is held to its place by a spring and operated by a lever in the same manner as is shown and described in the aforesaid Letters Patent, and I therefore have not deemed it necessary to show the same in the drawings.

The cross-head D in the Wilkerson chair as heretofore constructed has been fixed to the plunger, so as to be incapableof movement independent thereof. Under my improvement, however, the said cross-head, together with all the parts attached to or carried by it, is mounted and capable of oscillation laterally on trunnions c, which project from the front and rear,respectively, of a central hub, G, which is fast to the plunger or post A, as shown plainly in Fig. 3. The whole chair-body can thus be tilted laterally to one side or the other of perpendicular. The means for locking the chair in the position to which it may be thus adjusted are the same as those already described for securing the chair'in its backward or forward tilted position, consisting of the small sector G, attached to an arm, 0, projecting below the cross-head D from one side of the hub O, and a tapered locking-pin, K, working through a proper bearing, D, on the crosshead and loosely jointed to the lever M, which is pivoted at m to a boss attached to or formed on the under side of the cross-head D, the handle end of the lever being carried out to one side of the chair beyond the seat-frame in a position where it will be within convenient reach of the operator. A spring, L, attached at one end to the lever and at the other end to the cross-head, tends to throw the pin K into engagement with the sector G. The arm 0, at its outer end, is provided with a large hole to receive the pivot of the usual spittoon and bracket attachments, which are attached to this arm so that they may be kept in a perpendicularposition, no matter what may be the inclination of the chair-body.

Iam aware that before my invention a dentists chair has been made with its seat-frame connected to the base by a universal or gimbal joint. This I do not claim. Nor do I claim a broadly the application to a chair body or frame thus made capable of adjustment of two distinct locking mechanisms. I am not aware, however, of any dentists chair prior to my invention in which the seat or chair frame has been connected to the vertical central supporting-plunger through the intermediary of instrumentalities arranged and constructed to operate as hereinbefore described, and it is to this improvement that my claim is directed.

Having described my improvement, What I claim, and desire to secure by Letters Patent, 1s-

1. The combination, substantially as hereinbefore set forth, of the post or plunger, the oscillatory cross-head swiveled thereto, the oscillatory seat-frame swivelcd to the said crosshead so as to be capable of movingin a plane atright angles to the plane of oscillation of the cross-head, and independent locking mechanisms, substantially as described, the one lock-- ing the flame to the cross-head, the other looking the cross-head to the plunger 2. The plunger or post and its hub, provided with a lateral extension for supportingthe spittoon and bracket attachment, in combination with the oscillatory cross-head carried by and swiveled to the hub, the seat-frame carried by and jointed to the cross-head so as to be capable of independent oscillatory movement in a plane at right angles to the plane of oscillation of the cross-head, and independent locking mechanisms, substantially as hereinbcfore shown and set forth.

In testimony whereof I have hereunto set my hand this 7th day of January, 1881.

JOHN S. THOMPSON. 

